Apple’s newly appointed VP of Environmental Initiatives, and former head of EPA, Lisa Jackson spoke at Fortune’s Brainstorm Green conference earlier this week. The executive talked about a number of topics, including the iPad-makers various green projects.

Jackson noted that although Apple has done a good job reducing its carbon footprint over the past few years, it still has a long way to go. Their next major challenge, she says, is getting their 400+ retail stores around the globe to run on 100% on renewable energy…

Here’s the video of Jackson’s Fortune interview:

Here’s the bit on getting retail to go green:

It’s a lot harder to do the retail stores. They’re all over the place. In some places they’re in a mall…literally a shopping center. In some cases they’re standalone stores. But where they are in the grid and where they are in the world, the access to clean energy may or may not be a trivial exercise.

In addition to talking about Apple’s future green projects, Jackson touts that all of the company’s data centers are currently running on 100% renewable energy—thanks to large solar and fuel cell farms—and 94% of all its corporate facilities are renewable as well.